1. Field of the Invention
This invention relates to an improved process for converting methanol to ethanol by reaction with hydrogen and carbon monoxide.
2. Description of the Prior Art
U.S. Pat. No. 1,562,480 appears to be the earliest work which discloses the preparation of valuable oxygenated compounds via the homologation of methanol. In the process, carbon monoxide, hydrogen and methanol are reacted in the presence of a catalyst to produce high molecular weight alcohols, such as isobutanol, normal propanol, amyl alcohol and others. The reaction is carried out in vapor phase and the catalyst used is one having hydrogenation and hydrating constituents. Often the catalyst is promoted with potassium oxide, chromium oxide and zinc oxide.
U.S. Pat. No. 2,623,906 discloses the preparation of oxygen-containing organic compounds by reacting methanol, carbon monoxide and hydrogen at pressures exceeding 1,000 atmospheres in the presence of a cobalt-containing catalyst, e.g., cobalt acetate, cobalt propionate, cobalt isobutyrate, etc.
U.S. Pat. No. 3,285,948 is representative of recent art, (e.g., mid-60's) and discloses a process for producing ethanol by the catalytic interaction of methanol, carbon monoxide and hydrogen at a pressure of from about 1,000-15,000 psig and a temperature of about 175.degree.-230.degree. C. The interaction is carried out by utilizing a cobalt catalyst, an iodine promotor and a secondary promoter selected from the group consisting of ruthenium halides and osmium halides. Th patentee discloses the cobalt catalyst should be soluble in the reaction medium or form a cobalt carbonyl yielding compound. Examples of cobalt catalysts which can be converted to cobalt carbonyl forms include cobalt acetate, cobalt formate, cobalt propionate, etc.
U.S. Pat. No. 3,248,432 discloses an improved process for the synthesis of ethanol by reacting methanol, carbon monoxide and hydrogen in the presence of a water-soluble cobalt catalyst, iodine promoter and a phosphorous compound, e.g., diammonium phosphate.
U.S. Pat. No. 3,972,952 discloses a process for producing ethanol by the vapor phase reaction of methanol, hydrogen, and carbon monoxide in the presence of a solid catalyst, i.e., a support material impregnated with base promoters, e.g., oxides, hydroxides, or basic salts of an alalki or alkaline earth metal and metals of Periods 5 and 6 in Group 8 of the periodic table. Examples of inorganic base promoters include potassium or sodium oxide. The Period 5 and 6 metals of Group 8 include palladium, rhodium and platinum.